* {
  margin: 0;
  padding: 0;
  list-style: none;
}
.tab-block {
  width: 300px;
  margin: auto;
  border: 1px solid black;
}
.tab {
  margin: auto;
}
ul {
  display: flex;
  justify-content: space-around;
}
li {
  flex-grow: 1;
  text-align: center;
  cursor: pointer;
}
.tab-content {
  background-color: skyblue;
  width: 300px;
  height: 200px;
}
.active {
  background: skyblue;
}